This application is related to Japanese application No.2000-010451 filed on Jan. 19, 2000, whose priority is claimed under 35 USC xc2xa7 119, the disclosure of which is incorporated by reference in its entirety.
1. Field of the Invention
The present invention relates to a photovoltaic cell and a solar cell utilizing the photovoltaic cell.
2. Description of Related Art
Solar cells utilizing sunbeam have drawn attention as an alternative energy source to fossil fuels and various researches have been carried out. At present, solar cells made of polycrystalline silicon or amorphous silicon have been practically used as the mainstream. However, they are problematic in high costs and large energy consumption in manufacturing them and in the use of highly toxic materials such as gallium and arsenic.
According to Japanese Patent Kohyo No. HEI 5(1993)-504023, which corresponds to International Publication WO91/16719, published Japanese Patent No. 2664194 and International Publication WO94/05025, a wet type solar cell utilizing photoinduced electron transfer of a metallic complex has been disclosed as a novel solar cell.
The wet type solar cell is constructed of a semiconductor electrode, a counter electrode and an electrolyte layer sandwiched by the electrodes. Onto a surface of the semiconductor electrode which serves as a photoelectric conversion material, a photosensiting dye having an absorption spectrum in the range of visible rays is adsorbed.
Where the semiconductor electrode is irradiated with light, electrons are generated in the semiconductor electrode and transferred to the counter electrode through an electric circuit. The transferred electrons are carried by ions in the electrolyte layer and return to the semiconductor electrode. These steps are repeated to generate electric power.
However, in the wet type solar cell, electrical connection between the semiconductor electrode and the counter electrode is established by an electrolyte solution. Accordingly, leakage of the solution may possibly be occur, which brings unsatisfactory stability in the long term and complication of the manufacturing steps.
Regarding these drawbacks, Japanese Unexamined Patent Publication HEI 9(1997)-27352 has proposed the use of a solid electrolyte in the gel form. Further, Japanese Unexamined Patent Publication HEI 11(1999)-144773 has disclosed the use of an organic hole transport material in place of the electrolyte.
However, the solid electrolyte in the gel form also contains the organic solution so that the solution leakage cannot be avoided. Further, when using hole transport materials such as triphenylamine, the conversion efficience is extremely low, because these materials show poor hole transport mobility and it is difficult to transfer the hole from dye to counter electrode without bias.
In view of the above, an object of the present invention is to provide a photovoltaic cell with great stability and high conversion efficiency, as well as a solar cell utilizing the photovoltaic cell.
According to the present invention, provided is a photovoltaic cell comprising an electrode layer, a photovoltaic layer, a hole transport layer, a conductive layer and a counter electrode layer stacked in this order.
Still according to the present invention, provided is a solar cell comprising the above-mentioned photovoltaic cell.
These and other objects of the present application will become more readily apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.